1. Field of the Invention
The invention relates to a graphical indicator that is provided on the surface of an object and carries index information recognized by pattern/image recognition process.
2. Description of the Related Art
FIG. 1 shows a schematic diagram illustrating a graphical indicator 102 provided on the surface 100 of an object. The graphical indicator 102 typically consists of a plurality of graphical micro-units, and the graphical indicator 102 and the primary pattern or text 104 (such as the text “APPLE” shown in FIG. 1) that carries main information coexist on the surface 100 of an object such as a paper sheet. Since the graphical micro-units are so tiny as to be visually negligible or be sensed as background materials by human eyes, they do not interfere with the recognition of the main information carried by the primary pattern or text 104.
FIG. 2 shows a schematic diagram illustrating an electronic system 110 used to retrieve the information carried by graphical indicators. The electronic system 110 includes an optical device 112, an image-processing device 114, and an output device 116, and all of them are wired to each other or coupled with each other via wireless communication. The optical device 112 captures an enlarged image of the surface on which the graphical indicators 102 are formed, and then the image-processing device 114 fetches the graphical indicators 102 from the enlarged image and transforms them into digital data to retrieve the index information carried by the graphical indicators 102. Finally, the output device 116 receives the index information and then outputs the index information in a specific form. Hence, through the provision of the graphical indicators 102, more additional information can be appended to the surface of an object such as a paper sheet.
FIG. 3 shows a schematic diagram illustrating a conventional design of a dot pattern that includes multiple graphical indicators 102. As shown in FIG. 3, each graphical indicator 102 (indicated by dash lines) includes a key dot 202, multiple lattice dots 204, and multiple information dots 206 that are arranged in accordance with a predetermined rule. First, in each graphical indicator 102, a block is defined by a 5×5 matrix of lattice dots 204, and each information dot 206 is disposed neighboring a hypothetical center point of four lattice dots 204 that are arranged in a rectangle. More specifically, within each rectangle constructed by four lattice dots 204, the information dot 206 is placed slightly toward the top, down, left or right side of the hypothetical center point of the rectangle to represent different values recognized by the electronic system 110. The key dot 202, which is the representative point of each graphical indicator 102, is formed by unidirectional shifting the center lattice dot of a 5×5 matrix of lattice dots 204. Thus, the key dot 202 is designed to provide the graphical indicator 102 with a reference orientation when the optical device 112 captures an enlarged image from the surface of an object. Further, the manner where each four lattice dots 204 are arranged in a rectangle may help to correct the possible distortion or deflection of the captured image.
As shown in FIG. 1, since the primary pattern or text 104 that carries main information and the graphical indicator 102 that carries additional index information coexist on the surface of an object, a higher distribution density of micro-units may deteriorate the visual effect and raise the possibility of confusion between the graphical indicator 102 and the primary pattern or text 104. Further, when the graphical indicators 102 are spread on a confined surface area, a great amount of index information to be carried may cause an excess distribution density of micro-units to result in a considerable small space between two adjacent micro-units. This may further deteriorate the visual effect and raise the possibility of confusion, particularly when the micro-units are printed on a paper sheet. Though an approach of reducing the dimension of micro-units may cure this problem, a high-resolution printer must be provided to increase the cost and the complexity on printing the micro-units and the detecting errors of the optical device 112 are both increased. The conventional design such as shown in FIG. 1 always causes an excess distribution density of micro-units to result in the above problems.